This invention relates to an apparatus for intubation of the lacrimal duct (lacrimal drainage pathway) for treatments of lacrimal duct obstruction and dry eye.
As shown in FIG. 1, the lacrimal gland 14 secrete tears which drain into the inferior nasal meatus 18 via the lacrimal duct after moistening the ocular surface 17 having the cornea 15 and conjunctiva 16. The lacrimal duct consists of the upper punctum 1, lower punctum 2, vertical portion of the upper punctum 3, vertical portion of the lower punctum 4, boundary portion between the upper vertical and horizontal portions 5, boundary portion between the lower vertical and horizontal portions 6, upper horizontal portion 7, lower horizontal portion 8, common canaliculus 9, internal common punctum 10, lacrimal sac 11, nasolacrimal duct 12. The lower end 13 of the nasolacrimal duct 12 opens into the inferior nasal meatus 18.
In patients with dry eye having hypofunction of the lacrimal gland and deficiency of tears, tears which are very important for the eye immediately drain away via the lacrimal duct.
To suppress the tear drainage, occlusion of the upper punctum 1 and/or lower punctum 2 using electric cautery is performed. Occlusion using a punctal plug (mentioned later) inserted into the upper punctum 1 and lower punctum 2 is also performed.
By blocking the upper punctum 1 and lower punctum 2 like this, tears are accumulated in the conjunctival sac and dry eye symptoms disappear in many cases.
Dry eye symptoms include asthenopia, waking irritation, grittiness, foreign body sensation, scratchiness, soreness, difficulty to open the eyes in an air conditioned room, injection, burning and so on.
Recently, aggravation of dry eye symptoms by spending time in front of a monitor has become a problem. This is due to the fact that evaporation of tears is accelerated in individuals with tear deficiency by decreased frequency of blinking which is induced by looking at a monitor.
Artificial tears are added as eyedrops in another treatment of dry eye. But the ingredients of artificial tears are far from those of natural tears. It is best for eye to be wet with natural tears. Therefore, the treatment of punctal occlusion is superior.
Unlike artificial tears, tears contain lysozyme, lactoferrin, immunoglobulin, and so on which protect eye from bacteria and viruses. And some artificial tears contain a preservative which is harmful to the eye.
The roles of tears include an optical role wherein tears make smooth the microscopically irregular surface of the cornea 15 to improve eyesight, a role of lubricant wherein tears act as lubricant and the movements of eyelids become smooth, and other roles. Artificial tears can not be expected to play these various roles.
Therefore, occlusion of the upper punctum punctum 1 and/or lower punctum 2 to wet the eye with natural tears is superior. But punctal occlusion by argon laser may induce epiphora postoperatively. In such a case, punctal and canalicular surgery are needed to reconstruct canaliculi and puncta.
The use of a punctal plug is superior because a punctal plug can be removed easily in such cases.
In 1975 Freeman reported a punctal plug as shown in FIG. 2 for the treatment of dry eye. For example, see Freeman, J M: The punctum plug: evaluation of a new treatment for the dry eye. Trans Am Acad Ophthalmol Otolaryngol 79: op 874-879, 1975.
The punctal plug shown in FIG. 2 consists of the tip 21, shaft 22, brim 23 and there is a hole 24 in the center of brim 23. The hole 24 is continuous with a tubular lumen 25 of shaft 22 and the lumen 26 with a closed end 27 of the tip 21. The punctal plug shown in FIG. 2 measures 2.8 mm in total length, 1.5.about.2.0 mm in diameter of brim, 0.7 mm in height of brim, 1.5 mm in length of shaft and 0.7 mm in diameter of shaft.
The punctal plug in FIG. 2 is used as shown in FIG. 3. The punctal plug is inserted into puncta 1, 2 and vertical portion of canaliculus 3, 4, and the total length of the puncta 1, 2 and vertical portions of canaliculus 3, 4 is 2.5 mm on the average. Therefore, the total length 2.8 mm of the punctal plug is too long. Consequently, the brim 23 touches the cornea 28 and not infrequently induces a foreign body sensation.
FIG. 4 shows a punctal plug of the FCI company. This is also used for the treatment of dry eye in Japan. For example see, Junzo Hirano & Miki Hirano: Experience of the treatment for a case with Stevens-Johnson syndrome with severe keratoconus, Japanese Review of Clinical Ophthalmology 91:41-44, 1997.
The punctal plug in FIG. 4 is a miniaturized one. This punctal plug measures 1.7 mm in total length, 1.5 mm in diameter of brim 23, and is miniaturized as a whole. It measures 0.1 mm in thickness of brim 23 which inclines 20.degree. against the shaft 22.
The Punctal plug in FIG. 4 also consists of tip 21, shaft 22 and brim 23, and as in the punctal plug as shown in FIG. 2, hole 24 is continuous with the lumen 25 with closed end 27 of shaft 25.
In use, the tip 29 of the punctal plug is pushed into the lacrimal duct to or near the boundary portion 5, 6 between the vertical portion 3, 4 and horizontal portion 7, 8 of canaliculus, by a metal probe which is inserted through the hole 24 to the closed end 27.
FIG. 5 shows a punctal plug with a tapered shaft form. This plug is also miniaturized and consists of the tip 21, shaft 22 and brim 23. As in the punctal plug shown in FIG. 2, the hole 24 is continuous with lumen 25 with a closed end 27 of the shaft 22. The shaft 22 becomes gradually smaller as it tapers toward the brim 23.
Although corneal disorder is hardly induced by such a miniature punctal plug, the miniature punctal plug can migrate into the horizontal portion of canaliculus 7, 8 as shown in FIG. 6, and as shown in FIG. 7 into the lacrimal sac 11 and nasolacrimal duct 12, resulting in canaliculitis and dacryocystitis which sometimes need surgical intervention (For example, see Rumelt S et al: silicone punctal plug migration resulting in dacryocystitis and canaliculitis. Cornea 16: 377-399, 1997.).
Let us do a little more explanation in this respect. For dry eye, punctal plugs are inserted into puncta and left in place as shown in FIG. 3. But the punctal plug is apt to move because of the shallow insertion.
And as shown in FIG. 6, 7, the punctal plug can migrate into the lacrimal duct.
Furthermore, as shown in FIG. 2, FIG. 4 and FIG. 5, the edges of the tip 29 of either punctal plug are angular and sometimes stimulate canaliculus, resulting in the growth of pyogenic granuloma (For example, see Rapoza P A & Ruddat M S: Pyogenic granuloma as a complication of silicone punctal plug. Am J Ophthalmol 113: 454-455, 1992).
Stimulation by the tip 29 of punctal plug sometimes induces canalicular obstruction between the vertical portion 3, 4 and horizontal portion of canaliculus (For example, see Fayet B et al: Stenoses canaliculaires compliquant la pose de bouchouns lacrimaux. Incidence et mecanismus, J Fr Ophthalmol 15: 25-33, 1992.)
Granuloma sometimes pushes the punctal plug out of the puncta.
On the other hand, FIGS. 8.about.10 show various nunchaku style silicone tubings which are invented by this inventor. For example, see U.S. Pat. No. 2,539,325.
The apparatus for intubation of the lacrimal duct shown in FIGS. 8.about.10 consists of smaller soft tube 40, 41 and larger tube 42, 43 of a certain length, and the ends 47, 48 of the larger tube are closed.
Smaller tube 40, 41 extends between two larger tubes 42, 43, and the middle point 44 of the smaller tube 40, 41 is marked.
The smaller soft tube 40, 41 is connected with the larger tubes 42, 43. Two millimeter end lengths of the smaller tube 40, 41 are inserted into the larger tubes 42, 43 for connection. Therefore, the jointed portions 45, 46 are 2 mm in length. The tips 47, 48 of the larger tubes are sharp pointed and closed. For example, 2 mm tips of the tube are completely sealed with silastic adhesive, and then diagonally cut to taper the closed ends 47, 48. Small cuts 49 are made in the larger tubes 42, 43 parallel to the tubes 42, 43.
The junctions 45 make steps (shoulders) in the case of FIG. 8. As shown in FIGS. 9.about.10, it is possible to make tapered junctions 51 without steps.
And in the cases shown in FIGS. 9.about.10, the ends 53, 54 of the larger tube are conical in shape.
In the devices of FIGS. 8.about.9, it is very rare for the junctions 45 to separate. However, FIG. 10 shows a one piece tube without any junctions which consists of the smaller tube 40, 41 and larger tubes 42, 43 is made from the first.
1) In prior methods of monocanalicular intubation using the half size nunchaku-style silicone tubing shown in FIGS. 8.about.10 or a silicone tube of uniform diameter over its total length, it is necessary to fix the tube at the puncta 1, 2 with suturing because such tubing lacks the brim.
2) Prior punctal plugs shown in FIGS. 2.about.7 are angular, and cause stimulation which sometimes induces granuloma.
3) Further, punctal plugs shown in FIGS. 2.about.7, sometimes cause canalicular obstruction between the vertical portion 3, 4 and the horizontal portion 7, 8 of the canaliculus.
4) The punctal plugs shown in FIGS. 2.about.8 also create a problem in that they sometimes migrate into the canaliculus, lacrimal sac and nasolacrimal duct because their brim is circular and too small.
5) Prior art nunchaku-style silicone tubings shown in FIGS. 8.about.10 are sometimes difficult to insert from the puncta 1, 2 because the closed ends are not sufficiently sharp pointed.
6) Prior art punctal plugs shown in FIGS. 2.about.7, sometimes come out because of their shallow insertion.
7) Dry eye symptoms are sometimes aggravated in patients with both dry eye and dacryocystitis, after intubation using prior art tubes shown in FIGS. 8.about.10 and/or dacryocystothinostomy.
8) Punctal plugs shown in FIGS. 2.about.7, are not stable.
9) Tubes with the same diameter over their total length are not stable even if a brim is attached to them.
10) Prior art tubes shown in FIGS. 8.about.10 sometimes induce slitting of the puncta 1, 2 and canaliculi 3-8, as shown in FIG. 11.